1. Field of the Invention
The present invention relates to a vehicle headlamp for illuminating light to a forward direction of a vehicle by changing a light distribution pattern for low beam (light distribution pattern for passing) and a light distribution pattern for high beam (light distribution pattern for cruising).
2. Description of the Related Art
A vehicle headlamp of this type is conventionally known (Patent Document 1: Japanese Laid-open Patent Application No 2007-109493, for example). Hereinafter, a conventional vehicle headlamp will be described. The conventional vehicle headlamp is made up of: a first light source unit forming a light distribution pattern for low beam; and a second light source unit forming a light distribution pattern for high beam. The first light source unit is a projector-type lamp unit, and is provided with: a light source; an elliptical (convergent) reflector; a shade; and a projecting lens. In addition, the second light source unit is a projector-type lamp unit, and is provided with: a light source; an elliptical (convergent) reflector; and a projecting lens. Hereinafter, functions of the conventional headlamp will be described. When the light source of the first light source unit is lit, the light from the light source is reflected by means of the reflector; a part of the reflected light is cut off by means of the shade; a light distribution pattern having an oblique cutoff line and a horizontal cutoff line, i.e., a light distribution pattern for low beam is formed; and the light distribution pattern for low beam is longitudinally and transversely inverted from the projecting lens, and illuminated (projected) to a forward direction of a vehicle. In addition, when the light source of the second light source unit is lit, the light from the light source is reflected by means of the reflector, and the reflected light, as a light distribution pattern for high beam, is longitudinally and transversely inverted from the projecting lens, and is illuminated (projected) toward the forward direction of the vehicle.
Again, the conventional vehicle headlamp is made of: the first light source unit having the light source, the reflector, a shade, and the projector lens; and the second light source unit having the light source, the reflector, and the projector lens. Thus, the conventional vehicle headlamp requires a large number of components and the second light source unit for a light distribution pattern for high beam, and entails problems concerning downsizing, weight reduction, power saving, and cost reduction, accordingly.
The present invention has been made to solve problems concerning downsizing, weight reduction, power saving, and cost reduction, which could arise due to the fact that the conventional vehicle headlamp requires the second light source unit for a light distribution pattern for high beam.